1. Field of the Invention
The present invention relates to a variable length decoding device and a variable length decoding method capable of accelerating a load process of a variable length code particularly from a memory in a data process for processing a variable length code used in a technical field of a processor in a broad sense.
2. Description of the Related Art
In a conventional variable decoding device, a device exclusively used for the variable length decoding is provided so as to realize a high-speed operation. Further, a decoding process is more often executed by means of software these days to respond to the ongoing improvement of a processor, wherein the high-speed operation is realized by providing an exclusive instruction for the simultaneous renewals of a data reference and a reference position thereof and the like.
In the case of the conventional method in which the exclusive device is provided to thereby achieve the high-speed operation, when a plurality of data for image coding and audio coding using a variable length code was desirably handled, for example, it was necessary to provide a device exclusively used for the purpose for each data. Further, in the high-speed operation using the software process in the processor, it was necessary to execute a judgment process in compliance with a volume of consumption data and a plurality of resultant memory accesses, which undermined an expected level of high speed. Regarding the cited patent document 1, a judgment whether or not number of data, which were referred to among data in a buffer register, exceeds a threshold value and a judgment process for a shift process of the buffer register are included in the relevant invention. Further, another memory is further provided, or the buffer register is alternatively installed as a register exclusively used for the variable length decoding so as to retain a value of the buffer register because the value is different to a data layout at a source of data loading on a memory, which required such a process as saving/returning with respect to the memory. The relevant invention further required an extra monitoring and operation in order to renew an address.
A main object of the invention is to provide a variable length decoding device, a reproducing system comprising the device and a variable length decoding method capable of accelerating the variable length decoding in the pursuit of solving the foregoing problems and thereby achieving the high-speed operation in the software process.